The present invention relates to the protection of foodstuffs, beverages, pharmaceuticals, cosmetics, personal care products, shampoos and the like from the deleterious effects of ultraviolet radiation. It has been found that certain highly durable benzotriazoles and tris-aryl-s-triazines are especially effective towards this end when incorporated in the containers or films in which such materials are stored.
Many products such as certain fruit juices, soft drinks, beer, wines, food products, dairy products, cosmetics, shampoos, vitamins and pharmaceuticals are deleteriously affected, i.e. degraded, by the effects of ultraviolet (UV) light when packaged in plastic containers which allow the transmission of such light.
The use of UV absorbers towards protecting bottle and film contents is well known. However there is a trend towards the use of clear or lightly colored containers. More aesthetically pleasing containers may be formed from clear plastics which also allow one to view the contents. Unfortunately, clear and lightly colored containers and films allow the transmission of significant portions of ultraviolet light, i.e. light in the range of about 280 to about 400 nm. Further, there is a trend towards more light-weight and hence thinner walled containers. Thin-walled containers, by virtue of a shorter path length, will allow more UV light to pass. Due to these trends in packaging there is a need for more efficient UV absorbers for use in this area. UV absorber efficiency is a function of how strongly the molecule absorbs light across the entire UV region as well as its thermal and photostability, i.e. durability.
Many cooking oils and salad oils are now offered in clear PET [poly(ethylene terephthalate)] packaging. Practically all vegetable or seed-based oils such as soybean, olive, safflower, cottonseed and corn oils contain varying levels of unsaturated olefinic acids or esters (e.g. linoleates) which are susceptible to light-induced degradation. Most plant based oils also contain natural chlorophyll or other pigment photosensitizers. Pascall, et al., J. Food Sci., 60 (5), 1116 (1995), discuss the UV protection of soybean oil with the use of Tinuvin(copyright) 326 incorporated into coextruded, multi-layered, polypropylene-based containers. Tinuvin(copyright) 326 is a benzotriazole UV absorber, 5-chloro-2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-2H-benzotriazole, available from Ciba Specialty Chemicals Corp.
Milk is packaged in translucent or white pigmented HDPE bottles to reduce the amount of light transmission through the plastic. Fanelli, et al., J. Food Protection, 48(2), 112-117 (1985) disclose that Tinuvin(copyright) 326 in HDPE packaging is effective at reducing the loss rate of Vitamin A in milk exposed to cool white fluorescent light. Protection of vitamins is also of importance in fruit juices. In xe2x80x9cTropicana Twists Again,xe2x80x9d Packaging World, January 1999, p.2, it is disclosed that PET bottles containing a xe2x80x9cUV inhibitorxe2x80x9d are used to protect the shelf life of Vitamin C in fruit drinks.
The use of Tinuvin(copyright) 234, 2-(2-hydroxy-3,5-di-xcex1-cumyl)-2H-benzotriazole, Tinuvin(copyright) 326, 5-chloro-2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-2H-benzotriazole, Tinuvin(copyright) 327, 5-chloro-2-(2-hydroxy-3,5-di-tert-butylphenyl)-2H-benzotriazole, and Tinuvin(copyright) 1577, 4,6-diphenyl-2-(4-hexyloxy-2-hydroxyphenyl)-s-triazine, in packaging for content protection is known. In particular, the combinations of Tinuvin(copyright) 234 with either Tinuvin(copyright) 327 or Tinuvin(copyright) 326 are known.
It is well known that beer is normally bottled in amber or green-tinted glass to protect it from light. A highly efficient UV absorber would allow beer to be packaged in, for example, clear PET bottles.
U.S. Pat. Nos. 4,882,412, 4,892,923 and 4,950,732 disclose the use of 7-oxy-2H-1-benzopypran-2-one, 7-oxy-2H-1-benzopyran-2-imine, 3H-naphtho[2,1-b]pyran-3-one, 3H-naphtho[2,1b]pyran-3-imine and bis-methine moieties as UV absorbing groups to protect the contents of polyester and polycarbonate containers.
U.S. Pat. No. 5,948,458 teaches the protection of foods containing unsaturated lipids and fats from spoilage due to exposure to UV radiation by incorporation of calcium phosphate compounds either directly into the food product itself or in the food coatings and package wrap.
It has been found that certain UV absorbers of the class of durable benzotriazoles and tris-aryl-s-triazines are especially effective towards protecting the contents of clear, lightly colored and thin-walled containers and films.
The description, preparation and uses of the 2H-benzotriazole UV absorbers are described in U.S. Pat. Nos. 3,004,896; 3,055,896; 3,072,585; 3,074,910; 3,189,615; 3,230,194; 4,127,586; 4,226,763; 4,278,589; 4,315,848; 4,383,863; 4,675,352; 4,681,905 and 4,853,471.
U.S. Pat. Nos. 5,319,091 and 5,410,071 described the preparation of benzotriazoles substituted at the 5-position of the benzo ring with alkyl- or aryl-sulfonyl moieties. It is taught in U.S. Pat. No. 5,280,124 that by introducing a higher alkyl or aryl sulfoxide or sulfone at the 5-position of the benzo ring of the benzotriazole, the resulting benzotriazole exhibits enhanced absorption in the near visible range (over 350 nm). Such sulfone substituted products were shown to be useful in automotive coatings applications. U.S. Pat. Nos. 5,977,219 and 6,166,218 teach that an electron withdrawing moiety at the 5-position of the benzo ring of the benzotriazole is advantageous for similar reasons. Additionally, this patent and copending application teach that such an electron withdrawing group dramatically increases the photostability of these benzotriazole UV absorbers in automotive coatings. U.S. Pat. No. 5,574,166 teaches that benzotriazoles with a cumyl group ortho to the phenol are especially thermally stable. Surprisingly, these highly durable benzotriazoles are especially well-suited for the instant applications.
U.S. Pat. No. 3,218,332 discloses benzotriazoles substituted at the 5-position of the benzo ring by a lower alkyl sulfonyl moiety. U.S. Pat. Nos. 5,268,450 and 5,319,091 disclose polymer compositions and a process for the production of substituted aryl thio and aryl sulfonyl benzotriazoles which are covalently bound to polymers, such as poly(phenylene sulfide), RYTON(copyright), Phillips Petroleum. U.S. Pat. No. 5,280,124 discloses benzotriazoles with only higher alkyl or aryl sulfinyl or sulfonyl moieties at the 5-position of the benzo ring which are useful for protecting thermoset automotive coatings. U.S. Pat. No. 5,977,219 and the copending patent application mentioned above teach the use of certain electron withdrawing groups including some sulfonyl groups at the 5-position of the benzo ring for the stabilization of automotive coatings.
Japanese Patent No. 92-352228 discloses the use of 5-ethylsulfonyl benzotriazoles with the 3-position of the phenyl ring being unsubstituted or substituted by methyl for the UV protection of dust proof poly(vinyl chloride) resin films.
Copending application Ser. No. 09/303,583 teaches the use of this class of UV absorbers in adhesive compositions suitable for use as an adhesive layer in a laminated article or multi-layer construction. The laminated articles include solar control films, films and glazings, UV absorbing glasses and glass coatings, optical films and the like. The protection of interior structures, textiles and fabrics from UV induced photodegradation such as in automotive applications is discussed.
The description, preparation and uses of the s-triazine UV absorbers are described for automotive coatings, photographic application, polymeric film coatings and ink jet printing. Automotive coatings are described in British 2,317,174A and 2,317,893A and in U.S. Pat. Nos. 5,354,794; 5,556,973; 5,681,955; 5,726,309 and 5,106,891. Photographic applications are disclosed in U.S. Pat. No. 3,843,371 and copending application Ser. No. 08/974,263. Polymeric film coatings are described in U.S. Pat. Nos. 4,619,956 and 4,740,542. Ink jet printing is disclosed in U.S. Pat. No. 5,096,489. Tris-aryl-s-triazines with high molar absorption are described in copending application Ser. No. 09/383,163. From each of these patents, the s-triazine UV absorbers are revealed as very photostable.
The s-triazine UV absorbers can be prepared by the general synthetic procedures outlined in U.S. Pat. Nos. 5,726,309; 5,681,955 and 5,556,973; British 2,317,714A, WO 96/28431 and EP 941989A2.
It is known in the art that the concomitant use of a hindered amine light stabilizer with a UV absorbers such as benzotriazoles and s-triazines provide excellent stabilization in many polymer compositions as summarized by G. Bemer and M. Rembold, xe2x80x9cNew Light Stabilizers for High Solids Coatingsxe2x80x9d, Organic Coatings and Science and Technology, Vol. 6, Dekkar, N.Y., pp 55-85.